Frequently asked

Yes — completely free and open source, released under the GNU GPL v3.0. There's no paid tier and nothing to unlock.

Anyone with a smart telescope — it's built and tuned for the ZWO Seestar S30 Pro — who wants a finished image without learning a professional suite first. Nocturne walks you through the process one guided step at a time and explains the concepts as you go.

A stacked FITS master (.fit / .fits / .fts) — for example the file your Seestar produces after a session.

A 16-bit TIFF (.tif / .tiff) — a master you stacked in Siril, APP or DeepSkyStacker, or a picture you already finished elsewhere. Nocturne works out whether it is still unstretched, in which case the whole process applies, or already stretched, in which case it opens at the finishing steps. It tells you which it decided and lets you correct it in one click.

You can also point Nocturne at a folder of raw subs and let its built-in stacker grade and integrate them into a master first.

No — Nocturne opens an image and runs the whole pipeline with none of them. Two free ones are worth the ten minutes, though.

GraXpert (free) powers background/gradient extraction and one of the denoise options — recommended, and a quick install.

StarNet2 (free) separates stars from the rest of the image, which eleven of Nocturne's steps and tools depend on. The built-in fallback leaves about twice as much star flux behind, so this is the other one to install.

ASTAP (free) is optional — it adds plate-solving, target identification and annotation.

RC-Astro (paid) is entirely optional. Every step that can use it has a free fallback built in, so Nocturne is fully functional without it — it's simply a little better with it.

See Install & set up for exactly what to download and how to connect each one.

macOS on Apple Silicon (M1 or newer) and Linux on x86-64. The Linux build is made on Ubuntu 24.04, so it needs glibc 2.39 or newer. There is no Intel-Mac build and no Windows build yet — Nocturne is written in Python with cross-platform libraries, so both are feasible; they simply are not packaged.

Nocturne isn't notarized by Apple yet, so Gatekeeper is cautious on first launch. Right-click the app → Open → Open, or allow it under System Settings → Privacy & Security. You only need to do this once.

Nothing. All processing happens locally on your Mac; Nocturne doesn't send your images anywhere. The only exception is if you choose to share a stack through the voluntary "Lend your light" form on the home page — and that data is used only to test and improve Nocturne, never shared or republished.

Plate-solving is optional — it's only needed for target identification, annotation, and photometric colour calibration. If you want it, install ASTAP and its D05 star database from the ASTAP page, then point Nocturne at ASTAP in Settings. Full steps are in Install & set up.

Your images never leave your Mac. Nocturne opens, processes and exports everything locally — there is no account, no cloud and no upload. The only way an image of yours reaches me is if you deliberately send one.

Nocturne makes at most two network requests, and you can refuse both in Settings:

1. An update check. At startup it asks github.com whether a newer version has been released. Your IP reaches GitHub as part of that request, as it does for any web request; I receive nothing from it.
2. Usage counting, only if you say yes. Nocturne asks once, on first run. If you agree it sends {"event": "daily", "version", "id"} once a day and nothing else — the id is a random number for your installation that changes every month, and no IP address is stored. If you decline, nothing is ever sent and you are not asked again.

Why ask at all? Downloads say nothing about whether anyone actually uses the app, and that decides whether things like a proper support system are worth building. The full detail, including what is deliberately not collected, is on the privacy page.

Nocturne is designed around the Seestar S30 Pro (Sony IMX585 sensor), and its sensor read-outs and defaults are tuned for it. That said, it works on any one-shot-colour or dualband stacked FITS — you'll just miss the Seestar-specific niceties.